It is proposed to use Laser Doppler Anemometry and fluid dynamic measurement techniques to analyze flow past aortic valve prosthesis and the effect of various types of prosthetic valves in the flow development in a model of the human aorta. a model of the human aorta will be duplicated in acrylic from a casting made in situ. This model will include the complicated geometry of the human aorta including the sinuses of val salva and the arteries branching at the aortic arch. This model chamber will be mounted in our mock-circulatory system with various currently popular aortic valves mounted upstream to the arch model. Both qualitative studies using flow visualization techniques and quantitative studies using Laser Doppler Anemometry will be perfomred to critically evaluate the valve prosthesis and the flow past the prosthesis into the model of the human aorta.